Engines may use a turbocharger to improve engine torque/power output density. In one example, a turbocharger may include a compressor and a turbine connected by a drive shaft, where the turbine is coupled to the exhaust manifold side and the compressor is coupled to the intake manifold side. In this way, the exhaust-driven turbine supplies energy to the compressor to increase the flow of air into the engine.
Attempts to achieve high efficiency and wide flow range turbocharger compressor for improved engine power and fuel economy, especially for diesel engines, may include variable inlet compressor and variable vaned diffuser. However, those technologies may require actuation systems, which may increases costs and durability concerns. In addition, increased turbocharged engine power density may produce high pressure ratios and high temperature inside the compressor. High temperature provides various shortcomings including oil coking inside the compressor diffuser. This may cause a drop in compressor efficiency.
The compressor may be intended to work in an operating range between two conditions, surge and choke. Surge occurs during low air mass flow, when the air flow through the compressor stalls and may reverse. The reversal of air flow may cause the engine to lose power. One source of surge, tip-out surge, may occur when the engine suddenly decelerates. During tip-out surge, the engine and the air flow mass through the compressor may slow down, while the turbocharger continues to spin due to inertia and delays through the exhaust system. The spinning compressor and low air flow rate may cause rapid pressure build-up on the compressor outlet, while the lagging higher exhaust flow rate may cause pressure reduction on the turbine side. When forward flow through the compressor can no longer be sustainable, a momentary flow reversal occurs, and the compressor is in surge.
One solution to cool the turbine side of the turbocharger, which is subjected to very hot exhaust gasses, is disclosed in US 2011/0180026A1. A cooling jacket is provided in the wall of the turbine housing to allows fluid cooling. However, the inventors herein have recognized the compressor side of the turbocharger would benefit from more efficient cooling, for at least the reasons discussed herein.
In particular, in accordance with the present disclosure a turbocharger compressor to address the above issues is described. The turbocharger compressor may include an inlet configured to intake a charge gas at a first end and to direct the charge gas toward an impeller. A first coolant passage may be in thermally conductive contact with the charge gas in the inlet and fluidically coupled with a heat exchanger. An impeller region may surround the impeller downstream from the inlet, and a second coolant passage may be in thermally conductive contact with the impeller region and fluidically coupled with the heat exchanger. A diffuser region may be downstream from the impeller region, and a third coolant passage may be in thermally conductive contact with the diffuser region and fluidically coupled with the heat exchanger. In addition a volute region may be downstream from the diffuser region, and a fourth coolant passage may be in thermally conductive contact with the volute region and fluidically coupled with the heat exchanger. In this way, charge gases along the path through the compressor may experience particularly effective cooling. Also in this way, areas within the compressor that may have oil present may be less likely to experience oil coking. Also in this way a charge air cooler may be less burdened by particularly hot intake air.
Embodiments may also provide a turbocharger compressor wherein one or more coolant passages, for example the first or the second coolant passage may be configured such that coolant flows in an upstream direction relative to a general flow direction of charge gas through the compressor. In this way heat removal in the intake region may be particularly effective.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Finally, the above explanation does not admit any of the information or problems were well known.